There's a photo of Bogatyr as re-armed in "Kreiser Bogatyr" by R M Melnikov (Gangut series), the 130mm apparently replace: (1) the turret guns (4 guns), (2) the 152mm in casemates and shields on each side (8 guns), (3) the shielded 75mm between the casemate and the endmost shielded 152mm fore and aft each side (4 guns). Total 16 guns.
Edit to add:
From other photos in Oleg the aftmost 75mm position each side is the one that's left empty, plus turrets makes 16 again.
Kagul appears to have the same arrangement as Bogatyr.
Pamjat Merkuria has turrets replaced by single shielded guns, casemate guns replaced and first two shielded positions each side, total 10 guns.